While the debate over intel­li­gence rages on many fronts, the bat­tle over the impor­tance of hered­ity rages loud­est. It’s easy to see why. If the camp that argues intel­li­gence is 75 to 85 per­cent genet­i­cally deter­mined is cor­rect, then we’re faced with some tough ques­tions about the role of edu­ca­tion. If intel­li­gence is improved very lit­tle by schools, and if the IQ of the major­ity of the pop­u­la­tion will remain rel­a­tively unchanged no mat­ter how well schools per­form, then should school reform really be a priority?

More to the point, if our genes largely deter­mine our IQ, which in turn under­lies our per­for­mance through­out our lives, then what is the role of school? For some in this debate the answer to that ques­tion is sim­ply, “to be the best you can be.” But that seems lit­tle com­fort for those who aspire to “be” more than what their IQ cat­e­gory pre­dicts they will.

Those on the other side of this debate ques­tion whether hered­ity plays as big a role as the strong hered­i­tar­i­ans claim. And for the role it does play, they ques­tion whether hered­itabil­ity implies immutabil­ity. Hered­ity of height, for exam­ple, is about 90 per­cent, and yet aver­age height in sev­eral pop­u­la­tions around the world has been steadily increas­ing due to non-genetic influ­ences, like nutri­tion. If such a strong hered­i­tary trait can be rad­i­cally altered by envi­ron­men­tal factors–and height is but one exam­ple of this–then why is intel­li­gence different?

It is not, argues the camp that might best be described as intel­li­gence opti­mists. For them, the pes­simism that col­ors the strong hered­i­tar­ian posi­tion isn’t only dis­cour­ag­ing, it’s dan­ger­ous. Too much is hang­ing in the bal­ance for pes­simism about the poten­tial of our chil­dren to prevail.

Richard Nis­bett is a cham­pion of the intel­li­gence opti­mist camp, and with his lat­est book, Intel­li­gence and How to Get It: Why Schools and Cul­tures Count , he has emerged as the most per­sua­sive voice mar­shalling evi­dence to dis­prove the heredity-is-destiny argu­ment. Intel­lec­tual advance­ment, Nis­bett argues, is not the result of hard­wired genetic codes, but the province of con­trol­lable fac­tors like schools and social environments–and as such, improv­ing these fac­tors is cru­cially impor­tant. In the thick of con­tro­versy, he was gra­cious enough to spend a few min­utes dis­cussing his book with Neuronarrative.

My only com­plaint was with the her­i­tabil­ity of intel­li­gence per se. I just had the strong intu­ition that intel­li­gence, and cer­tainly IQ scores, were heav­ily influ­enced by the envi­ron­ment and by gene-environment inter­ac­tions. My research indi­cates that in fact her­i­tabil­ity, espe­cially for adult IQ, is sub­stan­tially less than fre­quently assumed.

One of the top­ics you dis­cuss in the book is that draw­ing infer­ences based on cor­re­la­tions often pro­duces mis­lead­ing results. What’s an exam­ple of this in the case of intelligence?

The cor­re­la­tion between iden­ti­cal twins reared apart gives an over­es­ti­mate of her­i­tabil­ity because the envi­ron­ments of iden­ti­cal twins reared apart are often highly sim­i­lar. But the main con­tra­dic­tion of her­i­tabil­ity esti­mates lies in the fact that adop­tion pro­duces a huge effect on IQ – much big­ger than could be explained if you believed the con­clu­sion of her­i­tabil­ity esti­mates based on sib­ling correlations.

You dis­cuss the impor­tance of early child­hood edu­ca­tion and pro­vide some com­pelling sta­tis­tics on the IQ-boosting effects of preschool. Why in a nut­shell is early edu­ca­tion so essential?

This is spec­u­la­tive at this point, but here goes. It is begin­ning to look like the IQ deficits of poor minor­ity kids begin extremely early and have to do with rear­ing tech­niques. Par­ents of such kids don’t talk to them much and don’t do things that would stim­u­late intel­li­gence. At any rate, we know of sev­eral social­iza­tion prac­tices that cor­re­late sub­stan­tially with IQ, and for all those prac­tices par­ents of poor minor­ity kids are on the low side.

If a child doesn’t receive qual­ity early edu­ca­tion, will he or she still be able to bridge the gap later on?

We do know that inter­ven­tions as late as early adult­hood can have a big effect on IQ and aca­d­e­mic achieve­ment. Col­lege reduces the IQ gap between blacks and whites from one stan­dard devi­a­tion (SD) to .4 SD. Just telling junior high school kids that their intel­li­gence is under their con­trol can pro­duce a gain in GPA. You can put a great deal of edu­ca­tional effort in at mid­dle school and junior high ages and pro­duce marked IQ and aca­d­e­mic achieve­ment gains.

You men­tion that chil­dren with greater self-control tend to have higher intel­li­gence. How are these linked, and is it rea­son­able to con­clude that increas­ing self-control raises intelligence?

This is spec­u­la­tive. We know there is a cor­re­la­tion between self-control and intel­li­gence, espe­cially between self-control and both ACT achieve­ment and SAT scores. What we don’t know is whether this rela­tion­ship is causal. I don’t doubt that it is, but I can’t prove it.

We now know that the brain isn’t a sta­tic entity, but rather pos­sesses remark­able plas­tic­ity – even, to a degree, well into adult­hood. In light of this, and your own research, is it pos­si­ble for adults to still boost their IQs?

We know that you can increase fluid intel­li­gence even in adults by some kinds of computer-game-like pro­grams. But that work is in its infancy. We know also that the hip­pocampi of Lon­don taxi dri­vers is 25 per­cent larger than nor­mal – due to an increase in the spa­tial rela­tions require­ments of the job.

I took away the sense from read­ing the book that you’re a hope­ful real­ist. If we could begin mak­ing changes to our edu­ca­tional sys­tem today, what do you think are the most impor­tant things we can do to cre­ate a brighter future for our kids?

Really effec­tive inter­ven­tion with par­ents of low socioe­co­nomic sta­tus infants to help them with social­iza­tion prac­tices, really good pre-K, KIPP-type ele­men­tary and mid­dle school.

I am hope­ful, for sure. In prin­ci­ple you could have all these things for the bot­tom third of socioe­co­nomic sta­tus fam­i­lies for less per year than the bailout of AIG. But I has­ten to say that we don’t really know how well any of the pro­grams shown to be effec­tive in demon­stra­tion projects would scale up.

– David DiS­alvo, a free­lance writer and research wonk who has writ­ten and lec­tured on top­ics involv­ing pub­lic health, air and water qual­ity, brand­ing, edu­ca­tion, energy effi­ciency, health­care and social mar­ket­ing. More info here. You can fol­low him on Twit­ter